Impact of White-Tailed Deer on Forest Communities within Brown County State Park Brown Parker 1997

1

Proceedings of the Indiana (1997) Volume 106

p.

Academy

39

of Science

39-51

IMPACT OF WHITE-TAILED DEER ON FOREST COMMUNITIES WITHIN

BROWN COUNTY STATE PARK, INDIANA Shannon

E.

Brown

School of Forestry and

Wood

Products

Michigan Technological University Houghton, Michigan 4993 and

George R. Parker Department of Forestry and

Wood

Products

Purdue University

West Lafayette, Indiana 47906

ABSTRACT: The

white-tailed deer (Odocoileus virginianus)

is

an herbivo-

rous species that can significantly influence the structure of forest ties

wherever

it

communi-

occurs in excessive numbers. This species has a propensity to

beyond the carrying capacity of its habitat when predation pressure The influence of white-tailed deer on the plant communities withIndiana's State Parks, which have been closed to hunting by man for sev-

increase is

in

reduced.

eral decades, are explored in this paper. During 1993 and 1994, sites (stratified by physiographic position) were sampled within Brown County State Park and adjacent State and National Forests (open to public hunting). A reduction in the percentage cover of the ground flora and the mature height of some specific plant species inside Brown County State Park as compared to external sites

subjected to hunting pressure

was noted.

In addition, the recruitment of

many woody species into larger size classes was reduced significantly within Brown County State Park. The current forest structure within Brown County State

for

Park indicates that

many

years.

mented within

this

The reduction

reduction in recruitment has been occurring in recruitment,

ture of the forests within the park

numbers

along with the damage docu-

the herbaceous layer, suggests that the sustainability and struc-

may

ultimately be affected unless deer

are controlled and the forest understory

KEYWORDS: Adiantum pedatum, Brown

is

County

allowed to recover.

State Park, Indiana, per-

centage cover, plant communities, species richness, white-tailed deer.

INTRODUCTION White-tailed deer, along with large predators, had been eliminated from Indi-

ana by 1900 (Mumford and Whitaker, 1982). In 1934, the Federal Aid to Wildlife Restoration (Pittman-Robertson Act) provided funds for the reintroduction of white-tailed deer into southern Indiana

(Mumford and Whitaker,

1982). These

introduced deer benefitted from a landscape of second-growth forests, openings,

and farmlands 1991).

that

had been created by logging, clearing, and agriculture (Smith.

Ecology:

40

By

Brown and Parker

Vol. 106 (1997)

1948, the Pittman-Robertson project reported an overabundance of

damage to agricultural and native plant communities, leadmodern hunt within 17 Indiana counties in 1951 (Mumford and

deer and deer-induced ing to the

first

Whitaker, 1982). State Parks in Indiana were closed to hunting and have remained so until recently. Restricted hunting has allowed the white-tailed deer populations in

some

State Parks to

expand beyond the capacity of their habitat

to sup-

port them.

Deer have a

selective foraging strategy

when food

resources are abundant,

but they change to a more generalist strategy as resources are depleted (Brown

and Doucet, 1991; Strole and Anderson, 1992; Kohlman and Risenhoover, 1994).

Selective foraging by a generalist species is a learned behavior which maximizes nutrient intake but

is

subject to constraints at

(Westoby, 1974). Deer are

known

low

levels of food availability

to select a species

according to

its

chemical

composition, and intake has been found to be constrained by forage toxicity

(Mc Arthur,

et ai, 1993).

These foraging

preference. Several studies

woody

browse species herbaceous and

strategies often lead to

that deer select certain

species over others (Korschgen, 1962; Nixon, et ai, 1970; McCaffery,

et ai, 1974).

This foraging strategy

model implies

may

show

termed the "optimization model," and the

is

that the grazing pressure

increase as that species

becomes

on a species within a plant community

rarer (Westoby, 1974).

Foraging strategies have been found to be sensitive to changes in plant avail-

(Kohlman and Risenhoover, 1994). Deer avoid nonpreferred browse when more preferred species become depleted. Deer search for and consume preferred forage until it becomes rare before switching to an apparently ability

species even

less desired species

(Gillingham and Bunnell, 1989). Deer density

may

also affect

food selection. Preferred foods, such as acorns, were found to be utilized more quickly by a larger deer population (McCullough, 1985;

Kohlman and Risen-

hoover, 1994). Therefore, at higher population levels, deer could significantly alter plant

communities by extirpating the more preferred species.

Evidence of intensive browsing by white-tailed deer in forest plant communities has been documented (Marquis, 1974; Alverson, et

and Anderson, 1992; Balgooyen and Waller, 1995) and found the regeneration of

some

tree species

by reducing

al.,

1988; Strole

to negatively effect

their recruitment

and survival

(Marquis, 1974; Strole and Anderson, 1992). This effect on regeneration has

been studied

in the eastern

hemlock (Tsuga canadensis)

forests of northeastern

Wisconsin, where, in areas that are heavily browsed, sugar maple (Acer sac-

charum) rapidly replaces hemlock (Anderson and Loucks, 1979). However, Anderson and Loucks (1979) also found that once browsing pressure was relieved, the hemlock recovered. Their finding suggests that a species subject to intensive browsing may recover if the pressure is reduced. In addition, the amount of browsing pressure on certain preferred forage species could be used as an indicator of deer abundance within an area (Korschgen, 1962).

In 1993, a committee was established by the Indiana Department of Natural Resources to develop alternative solutions for managing the excessive popu-

1

Vol.

1

06

( 1

Indiana

997)

Academy

lation of white-tailed deer within

4

of Science

Brown County

mittee concluded that the deer were seriously

State Park, Indiana. The comdamaging understory vegetation

and recommended a limited hunt within the park boundaries. This hunt occurred in

December 1993. The committee

also initiated a study to investigate the effects

of overbrowsing on understory vegetation (Brown County State Park Deer Study

Committee, 1993). The forest communities within Brown County State Park, Yellowwood State Forest, and Hoosier National Forest (the latter two are both

open

to hunting)

were sampled

Purdue University) tion.

the

to

in

1993 by James Van Kley (a Ph.D. student

at

determine the impact of white-tailed deer on the vegeta-

Preliminary measurements of the structure of the plant community and

browse damage within Brown County State Park indicated

that the deer

were

browsing heavily on selected herbaceous and woody species and significantly reducing the percentage cover, species richness, and mature heights of the ground flora species. This study also

found a difference between the southwestern cor-

Brown County State Park, with the southwestern cordamage (Parker and Van Kley, 1993). Parker and Van Kley that because the southwestern corner was bordered by Yel-

ner and the main body of

ner showing less

(1993) theorized

lowwood

State Forest

and Hoosier National Forest, the deer

in the

southwestern

corner of Brown County State Park experienced more hunting pressure than those

within the main body of the park.

Permanent study areas were not established by Van Kley to observe trends browse damage. Therefore, the current study was initiated in the spring of 1994 to determine the structure and composition of the plant communities following the removal of 392 deer in December 1993. Permanent plots were established to monitor changes in the plant communities in response to long-term change in deer populations. in

STUDY AREAS Brown County in

1929 and

is

was first opened The park is locat-

State Park, located in south-central Indiana,

Indiana's largest State Park at 6,358 hectares.

ed within the Brown County Hills Section of the Highland

Rim Natural Region

(Homoya, et al., 1985). This area is defined by acid silt loam soils with a small amount of loess and characteristic topographic features such as deeply dissected uplands, steep slopes, and narrow hollows (Homoya, et aL, 1985; Van Kley and Parker, 1993). Uplands are dominated by oak-hickory forest (Homoya. et al, 1985); common plants on the upper slopes are chestnut oak (Quercus prinus), common greenbrier (Smilax rotundifolia), low growing shrubs, and sedges (in particular, painted sedge {Carex picta)). The ravines contain mesic species (Homoya, et ah, 1985) such as beech (Fagus grandifolia), red oak {Quercus rubra), sugar maple (Acer saccharum), and white ash (Fraxinus americana).

Control areas were selected within Yellowwood State Forest and the Pleasant Run Unit of the Hoosier National Forest, which border the southwestern section of Brown County State Park. Both the State and National Forests are open to annual deer harvest.

42

Ecology:

Brown and Parker

Vol. 106 (1997)

METHODS Twenty

lowwood

sites

within

Brown County

State Park

State Forest/Hoosier National Forest

and ten control

sites in Yel-

were randomly selected

to estab-

The 20 sites in the park were divided into eight sites in the southwestern corner, where less browsing was observed (Parker and Van Kley, 1993), and 12 in the main body of the park. The Ecological lish

permanent study

plots.

System developed for the Pleasant Run Unit of Hoosier Nationwas used to determine similar physiographical units inside and outside park (Van Kley and Parker, 1993). Sites were limited to closed-canopy, rel-

Classification al

Forest

the

atively

mature forests and divided into four ecological landtypes: mesic norther-

ly or northeasterly slopes, dry southerly or southwesterly slopes,

mesic bottomlands,

and dry ridges. One or a combination of these landtypes were sampled at each site; a total of 19 landtypes were sampled in Yellowwood State Forest/Hoosier National Forest, 16 within the southwestern corner of Brown County State Park,

and 27

in the

main body of Brown County

State Park. All the sites

were sam-

pled within two months of each other to avoid site-to-site variation.

The following vegetative plots at

variables

were measured using a

each sample location: the percentage cover of the ground

series of nested flora, the species

richness of the ground flora, and the stem density and species richness of the

= < 50 cm in height; 2 = 50 to 200 = > 200 cm in height and < 2.5 cm dbh; and 4 = > 200 cm in height and > 2.5 cm dbh). The mature heights of six herbaceous species were

woody

cm

species within four size classes (1

in height; 3

also recorded.

The percentage cover of the ground line transect

sured

at

a

flora

was measured using a ten-meter

running parallel to the contour of the slope in each landtype mea-

site.

The length of overlap (cm) for the ground flora, including both woody class 1 was recorded and used to calculate the percent-

herbaceous and

,

age cover for each species.

To record the number of stems and woody species in classes 1 and 2, a one meter by ten meter belt transect was established using the ten-meter line transect as its lower edge. The dbh of woody species in classes 3 and 4 was recorded within a 100 m circular plot, the center of which was the start of the line 2

transect.

Ground

flora richness in

the herbaceous species

each landtype was determined by recording

found within the

belt transect

all

and circular plot. The species

present within the circular plot were determined by walking concentric circles

from the outer edge to the center.

Six species were chosen to test for differences

in

mature plant height with-

Yellowwood State Forest/Hoosier National Forest, the southwestern corner of Brown County State Park, and the main body of Brown County State Park.

The chosen species showed dramatic differences in mean mature height in heavily browsed areas relative to less impacted ones (Parker and Van Kley, 1993).

The species measured were: maidenhair fern (Adiantum pedatum), Jack-in-thein

pulpit (Arisaema triphyllum), wild licorice

{Galium circaezans), sweet cicely

Vol.

1

06

( 1

(Osmorhiza

Academy

43

997)

Indiana

claytonii),

Christmas fern {Polystichum acrostichoides), and com-

of Science

mon greenbrier (Smilax rotundifolia). To determine mature height, measured along the stem

to the

the forbs

were

node with the highest leaf or whorl of leaves. For

Christmas fern, the length of the longest frond was measured. Three to five plants of each species were measured within each belt transect and their heights were

averaged to determine the mean height of the species. The percentage cover was also calculated for these species.

One-way

analysis of variance

tion variables

among

was used

the sites within

National Forest, the southwestern corner

main body of Brown County

State Park.

to

compare the means

for vegeta-

Yellowwood State Forest/Hoosier of Brown County State Park, and the

For tests of mature height and percentage

cover of the individual species, only the landtypes in which the species were

known

to

be

common were

used. These included mesic slopes and bottom-

lands for maidenhair fern, Jack-in-the-pulpit, wild licorice, sweet cicely, and

Christmas

fern. All sites

were used for

common

greenbrier.

An

alpha level of

P < 0. 10 was used to delineate significant differences in the vegetation variables among

the three sample areas.

RESULTS The average number of species was not significantly different in the three areas (Table 1). However, on average, more species were found in all landtypes in Yellowwood State Forest/Hoosier National Forest and the southwestern corner of Brown County State Park than in the main body of the park. The percentage cover of the ground flora was significantly reduced in the main body of the park compared to both its southwestern corner and the areas outside the park. The coverage of the ground flora averaged only 14.4% per sample site in all landtypes within the main body of Brown County State Park as compared to 27.8% in the park's southwestern corner and 21.7% in Yellowwood State Forest/Hoosier National Forest. The greatest difference in percentage cover of the ground flora was found on mesic and bottomland sites. Coverage within the main body of Brown County State Park was 50% less than in Yellowwood State Forest/Hoosier National Forest.

Specific species exhibited differences in their percentage cover within the

park when compared to the control areas (Table

2).

Maidenhair fern and sweet

cicely both exhibited a significantly lower percentage cover inside the south-

western corner and in the main body of the park

when compared to Yellowwood

Sweet cicely did not intersect the tranany sites and only overlapped the transect at 0.3% of the sites in the main body of the park as compared to 1.5% in Yellowwood State Forest/Hoosier National Forest. Christmas fern showed a significantly higher percentage cover in Yellowwood State Forest/Hoosier National Forest and the southwestern corner of the Brown County State Park relative to the main body of the park, where it averaged 0.9% per sample site. Common greenbrier had a significantly higher percentage cover in Yellowwood State ForState Forest/Hoosier National Forest.

sect within the park's southwestern corner at

44

Ecology:

Brown and Parker

Vol. 106 (1997)

measured within a 10 m belt transect and a 100 m circular plot, and the percentage cover of the ground flora measured on a 10 m line transect observed at sample locations outside Brown County State Park, in the southwestern corner of Brown County State Park, and in the main body of Brown County Table

1.

Mean ground

2

flora richness

2

State Park during 1994.

Row means

with different letters are significantly different

(P<0.10).

Variable

Sampled

at

Yellowwood

Each

Ecological Landtype

All Sites (n

Ground

flora richness

Mesic Bottomlands

(n

=

flora richness

Mesic Slopes

(n

Ground

flora richness

(n

=

Ground

County State Park

flora richness

(n

21.5 a

22.1a

19.8 a

21.7 a

27.8 a

14.4 b

32.0 a

30.1 a

28.9 a

33.7 a

40.9 a

14.5 b

24.6 a

24.2 a

21.5 a

18.0 a

22.0 a

8.0 b

15)

Percentage cover of ground flora

Dry Ridges

Main Body of Brown

= 22)

Percentage cover of ground flora

Dry Slopes

State Park

15)

Percentage cover of ground flora

Ground

Southwestern Corner of

Brown County

= 62)

Percentage cover of ground flora

Ground

State and

Hoosier National Forests

=

13.6 a

14.0 a

12.8 a

22.3 a

34.9 a

23.1a

7.5 a

15.3 a

13.0 a

11.2a

14.7 a

12.2 a

10)

flora richness

Percentage cover of ground flora

est/Hoosier National Forest than in either area of the park.

The percentage cover

of greenbrier was significantly greater in the southwestern corner relative to the

main body of Brown County

State Park. Jack-in-the-pulpit

displayed no significant differences in coverage

The mean heights of also to

compared (Table

be significantly

among

and wild

licorice

the three areas.

the mature plants for the six selected species

2). Jack-in-the-pulpit

taller in

Yellowwood

and

were

common greenbrier were found

State Forest/Hoosier National Forest

than in both the southwestern corner and main body of Brown County State Park.

Maidenhair fern and Christmas fern were significantly shorter in the main body of Brown County State Park when compared to the southwestern corner of the park and Yellowwood State Forest/Hoosier National Forest. Both Jackin-the-pulpit and maidenhair fern were approximately 10 cm taller within Yel-

lowwood

State Forest/Hoosier National Forest than in both the southwestern

corner and the main body of the park. in

Yellowwood

Common greenbrier averaged 45 cm taller

State Forest/Hoosier National Forest

when compared

to

both

Vol.

1

06

( 1

Indiana

997)

Academy of Science

45

The mean percentage cover and mean height for selected species observed with2 belt transect at sample locations outside Brown County State Park, in the southwestern corner of Brown County State Park, and in the main body of Brown County State Park during 1994. The values used are from landtypes where the species was common. Row means for heights and percentage cover of the ground flora with different letters are significantly different (P < 0.10).

Table

2.

in a 10

m

Critical Species

Yellowwood

and

Adiantum pedatum

and

Main Body of Brown

Southwestern Corner of

Brown County

State Park

County

State Park

'

Percentage cover

Height (cm)

Arisaema triphyllum

2.3 a

0.4 b

0.1b

31.1 a

32.2 a

22.0 b

1

Percentage cover

Height (cm)

Galium circaezans

State

Hoosier National Forests

Variable Tested

0.9 a

0.9 a

1.2 a

22.3 a

12.9 b

12.0 b

0.1a

0.07 a

0.08 a

15.4 a

15.0 a

14.6 a

1

Percentage cover

Height (cm)

Osmorhiza claytoniV Percentage cover

0b

1.5 a

Height (cm)

Polystichum acrostichoides

0.3 b

11.2b

24.0 ab

35.2 a

x

Percentage cover

Height (cm)

4.7 a

2.8 a

0.9 b

51.5 a

41.9 a

26.5 b

Smilax rotundifolia 2 Percentage cover

Height (cm) 1

2

4.9 a

3.1b

2.1c

141.1a

95.9 b

93.1b

Mesic slopes and bottomlands.

All

sites.

Brown County

areas within

Yellowwood and 11.2

Sweet cicely was

significantly taller in

State Forest/Hoosier National Forest than in the

park, averaging 35.2 est

State Park.

main body of the

cm within Yellowwood State Forest/Hoosier National For-

cm within the main body of Brown County

displayed no significant difference in

mean

height

State Park.

among

Wild

licorice

the three sampling

areas.

Overall, the

number

for

the southwestern corner of

woody stems (class 1) was significantly greater in Brown County State Park relative to Yellowwood

and the main body of the park (Table 3).

The greatest difference occurred on mesic slopes and dry ridges where the numState Forest/Hoosier National Forest

46

Brown and Parker

Ecology:

Table

The number of stems

3.

size classes recorded at

western corner of

sample

for

woody

species and the species richness within four

sites outside

Brown County

Vol. 106 (1997)

of

State Park,

Brown County

and

in the

State Park, in the south-

main body of Brown County

Row means with different letters are significantly different = stems < 50 cm in height, size class 2 = stems 50 to 200 cm in height, size class 3 = stems > 200 cm in height and < 2.5 cm dbh, and size class 4 = stems > 200 cm in height and > 2.5 cm dbh. The density of size classes 1 and 2 are State Park during 1994.

(P < 0.10). Size class

per 10

m

2

plot

and for

Critical Species

and

Variable Tested

1

size classes 3

and 4 are per hectare.

Yellowwood

State and

Hoosier National Forests

Southwestern Corner of

Brown County

State Park

Main Body of Brown County

State Park

All Sites

Size class

1

39.6 a

67.6 b

39.4 a

8.4 a

8.8 a

6.1b

Density

1.3 a

0.6 ab

Species richness

0.8 a

0.5 a

0.04 b

405 a

94 b

159 b

1.8 a

0.7 b

932 a

831a

47.0 a

45.3 a

8.5 a

10.0 a

Density Species richness Size class 2

0.2 b

Size class 3

Density Species richness

1.0

b

Size class 4

Density

833 a

Mesic Bottomlands Size class

1

Density Species richness

48.0 5.9 b

Size class 2

Density

1.0 a

0.3 a

0.6 a

Species richness

1.0 a

0.2 b

0.14 b

200 a

75 a

143 a

1.0 a

0.8 a

0.9 a

Size class 3

Density Species richness Size class 4

a

671a

38.9 a

90.0 b

30.3 a

8.1 a

7.3 a

5.5 a

Density

2.0 a

0.8 ab

Species richness

1.0 a

0.6 a

0b 0b

700

Density

a

750

Mesic Slopes Size class

1

Density Species richness Size class 2

Size class 3

Density Species richness

450

a

150 b

175 b

2.4 a

0.8 b

1.1b

875 a

833 a

838 a

Size class 4

Density

Vol. 106 (1997)

Indiana

Academy

47

of Science

Table 3 (Continued) Critical Species

Yellowwood

and

State

and

Hoosier National Forests

Variable Tested

Southwestern Corner of

Brown County

State Park

Main Body of Brown County

State Park

Dry Ridges Size class

1

Density

18.0 a

73.3 b

25.0 a

6.0 a

9.0 b

5.6 a

43.4 a

46.7 a

51.6a

9.8 a

9.7 a

7.3 a

Density

0.7 a

0.7 a

Species richness

0.6 a

0.5 a

0b 0b

Species richness

Dry Slopes Size class

1

Density Species richness

Dry Slopes and Ridges Size class 2

Size class 3

471a

50 b

1.7 a

0.5 b

0.9 b

1128 a

883 a

925 a

Density Species richness

142

c

Size class 4

Density

ber of stems in the southwestern corner of the park averaged 90.0 and 73.3, respectively.

Dry

slopes and mesic bottomlands did not exhibit any significant

among the three areas.

The number of species observed

differences

in the

one meter by ten meter

belt transect

Yellowwood State Forest/Hoosier National Forest and the southwestern corner of Brown County State Park than in the main body of the park. The difference was most evident in the mesic bottomland sites in Brown County State Park which averaged 5.9 species per sample site compared to 8.5 in Yellowwood State Forest/Hoosier National Forest and 10.0 in the southwestern corner of the park. The other landtypes did not show was

significantly higher for all landtypes in

any significant differences with the exception of dry ridges, where a significantly higher number of species was observed in the southwestern corner of

County

State Park than in either

Yellowwood

Brown

State Forest/Hoosier National For-

main body of the park. overall number of stems for all woody species (class 2) per sample site for all landtypes was significantly higher in Yellowwood State Forest/Hoosier National Forest when compared to the main body of the park (Table 3). Sites averaged 1,300 stems per hectare in Yellowwood State Forest/Hoosier National Forest as compared to 200 stems per hectare inside the main body of the park.

Mesic slopes as well as dry slopes and ridges also exhibited this pattern: howest or the

The

ever, significant differences

western corner of

were not observed for these landtypes in the southState Park relative to either Yellowwood

Brown County

Ecology:

48

Brown and Parker

State Forest/Hoosier National Forest or the

main body of

Vol. 106 (1997)

the park.

Mesic bot-

tomlands did not show any significant differences among the three areas. The

number of woody species in size class 2 was also significantly higher in Yellowwood State Forest/Hoosier National Forest and the southwestern corner of Brown County State Park than in the main body of the park, where papaw (Asimina triloba) was the only species found on transects (Table 3).

The number of woody stems (class 3) per hectare was significantly reduced on all sites except mesic bottomlands within the park when compared to Yellowwood State Forest/Hoosier National Forest (Table 3). Species richness for this size class followed the same pattern (Table 3). Significantly more species per sample site were found within Yellowwood State Forest/Hoosier National Forest,

which averaged

1.8 species

per sample

site,

than in the southwestern cor-

ner (0.7) or the main body (1.0) of the park.

The number of woody species (class 4) per hectare was not significantly different inside Brown County State Park when compared to Yellowwood State Forest/Hoosier National Forest (Table 3). The number of stems averaged 932 per hectare for all landtypes within Yellowwood State Forest/Hoosier National Forest as compared to 831 in the southwestern corner and 833 in the main body of the park, respectively. This pattern was observed for all the different landtypes.

The same vegetation variables were also measured in 1993 within Brown County State Park and Yellowwood State Forest/Hoosier National Forest by Van Kley, and the means of these variables show similar trends between the two years (Table 4). For example, the average number of ground flora species per site found outside the park in 1994 was similar to the number found in 1993 (21.5 in 1994 and 23.3 in 1993). However, the number of species found per site in the southwestern corner and main body of Brown County State Park was higher in 1994. Percentage cover of the ground flora was similar in both years within the main body of Brown County State Park, averaging 14.4% in 1994 and 14.7% in 1993. However, Yellowwood State Forest/Hoosier National Forest exhibited a slightly lower percentage cover, and the southwestern corner of Brown County State Park exhibited a higher percentage cover in 1994. The southwestern corner of

Brown County

State Park also exhibited an increase in the

num-

ber of seedlings in 1994. In contrast, sapling numbers stayed constant between the

two sampling seasons.

DISCUSSION Excessive browsing within

numbers and

sizes for

Alverson, et

al.

some

Brown County

State Park has resulted in reduced

plant species, a conclusion consistent with those of

(1988) and Balgooyen and Waller (1995). These researchers

found that white-tailed deer could directly and indirectly affect the abundance

and structure of many herbaceous species, thereby influencing forest composition.

Likewise, Balgooyen and Waller (1995) indicated that

species, especially preferred

browse

species,

many herbaceous

were jeopardized by high deer den-

Vol. 106 (1997)

Indiana

Academy

49

of Science

4. The mean species richness and percentage cover of the ground flora as well as mean density of woody stems in size classes 1 and 2 recorded at sample sites outside Brown County State Park, in the southwestern corner of Brown County State Park, and in the main body of Brown County State Park during 1993 (Parker and Van Kley, 1993). Row means with different letters are significantly different (P < 0.10). Size class 1 = stems < 50 cm in height, and size class 2 = stems 50 to 200 cm in height.

Table the

Critical Species

and

Yellowwood

State

and

Hoosier National Forests

Variable Tested

Southwestern Corner of

Brown County

State Park

Main Body of Brown County

State Park

All Sites

Ground

23.3 a

16.6 b

14.7 b

Percentage cover of ground flora

34.1 a

18.6 b

14.6 b

Woody Woody

1

33.3 a

23.7 b

13.9 c

size class 2

3.9 a

0.5 b

0.4 b

flora richness

size class

Mesic Bottomlands

Ground

34.8 a

22.4 b

20.8 b

Percentage cover of ground flora

39.0 a

28.3 a

13.1b

Woody Woody

1

47.2 a

13.2 b

8.8 b

size class 2

5.0 a

0.6 b

0.5 b

17.1b

flora richness

size class

Mesic Slopes

Ground

30.3 a

21.3 b

Percentage cover of ground flora

32.4 a

10.9 b

8.0 b

Woody Woody

1

35.8 a

16.9 b

11.5b

size class 2

4.0 a

0.1b

0.5 b

flora richness

size class

Dry Slopes Ground

9.9 b

14.0 a

12.1 ab

Percentage cover of ground flora

29.2 a

23.6 a

21.2 a

Woody Woody

25.6 ab

33.9 a

16.8 b

sities.

flora richness

size class

1

size class 2

The

0.8 b

4.6 a

significant reduction in both percentage

of several herbaceous species within

0.2

b

ground cover and the

Brown County

State Park

size

when com-

pared to Yellowwood State Forest/Hoosier National Forest indicates that the deer population had exceeded the carrying capacity of their habitat within the park.

The southwestern corner of Brown County

State Park

was

less affected

by

deer browsing than the main body of the park in both 1993 and 1994. The shared

boundary with Yellowwood State Forest/Hoosier National Forest might have allowed increased hunting pressure in the southwestern corner of the park.

No

consistent significant difference for

woody stem

density (class 1)

was

found between the park and the State and National Forests. However, the higher number of woody stems (class 2) outside the park when compared to both areas within the park suggests that the trees are successfully reproducing, but

repeated browsing prevents seedlings from growing into the larger size classes.

Ecology:

50

Brown and Parker

Vol. 106 (1997)

Marquis (1974) found that browsing by white-tailed deer on the Allegheny Plateau in Pennsylvania prevented stems from growing beyond the seedling stage. His conclusions agree with those of Frelich and Lorimer (1985) and Anderson and

Katz (1993),

who both concluded that browsing by white-tailed deer was

ly affecting the reproduction

severe-

and recruitment of eastern hemlock into larger

size

classes.

The

large

number of plant

species

still

found within Brown County State

Park in 1993 and 1994 indicates a potential for recovery of the plant ties if

deer populations are maintained

at

lower

levels.

communi-

Other researchers have

numbers can effectively decrease browse Frelich and Lorimer, 1985; Alverson, et ah, 1988; Anderson and Katz, 1993). Anderson and Loucks (1979) suggest that wildlife should be maintained at a level that would not be detrimental to important tree species. They also suggest that in areas where wildlife is having also suggested that controlling deer

damage (Anderson and Loucks, 1979;

a detrimental effect, hunting regulations should be relaxed to prevent changes in tree species composition. Significant

occur within a few years

if

improvement

in the understory could

deer numbers were maintained

at

lower levels (Ander-

son and Loucks, 1979). However, a significant period of time will be needed before the forest can completely recover. Anderson and Katz (1993) suggest that the time needed for recovery after release

portional to the time the forest

The

from browsing pressure

was subjected

is

directly pro-

to this pressure.

392 deer (17 deer per square mile or 2.590 km 2 ) from 1993 may have been responsible for the slight improvement in the

limited removal of

the park in

condition of the understory vegetation.

found per

site

An increase in the number of plant species

occurred within the park in 1994. However, this increase in species

number might be

the result of deer reduction or annual variation. Before con-

crete conclusions can be reached about the specific

damage caused by

deer,

more

data needs to be collected during subsequent growing seasons. Continued studies

of the understory vegetation could show not only differences in the degree

of impact due to white-tailed deer browsing but also variation in the vegetation

due

to

annual variability and the timing of sampling within the growing sea-

son.

ACKNOWLEDGMENTS The authors would like to thank the Indiana Department of Natural Resources for financial support. They would also like to thank Jim Eagleman and the staffs at Brown County State Park and Yellowwood State Forest for their assistance with this project. A special thanks to Amanda Mcintosh and Sally Weeks for aiding with data collection.

LITERATURE CITED Alverson, W.S., D.M. Waller, and S.L. Solheim. 1988. Forests too deer: Effects in northern Wisconsin. Cons.

Biol. 2: 348-358.

Anderson, R.C. and A.J. Katz. 1993. Recovery of browse-sensitive tailed deer

tree species following release

from white-

(Odocoileus virginianus Zimmerman) browsing pressure. Biol. Cons. 63: 203-208.

Vol.

1

06

( 1

Indiana

997)

Academy

of Science

5

and O.L. Loucks. 1979. White-tailed deer (Odocoileus virginianus) influence on structure and composition of Tsuga canadensis

forests.

J.

Appl. Ecol. 16: 855-861.

Balgooyen, C.P. and D.M. Waller. 1995. The use of Clintonia borealis and other indicators of white-tailed deer on plant communities

Brown County

State Park

in

northern Wisconsin,

Deer Study Committee. 1993.

ana Dep. Natur. Res., Indianapolis, 12 pp.

G.J. Doucet. 1991. Temporal changes

Brown, D.T. and

ern deer yard.

Frelich, L.E.

USA.

Natur. Areas

to J.

gauge impacts 308-318.

15:

A report to the Natural Resources Commission. Indi-

in winter diet selection

by white-tailed deer

and C.G. Lorimer. 1985. Current and predicted long-term effects of deer browsing

forests in

in a north-

Wildlife Manage. 55: 361-376.

J.

Michigan,

USA.

in

hemlock

Biol. Cons. 34: 99-120.

Gillingham, M.P. and F.L. Bunnell. 1989. Effects of learning on food selection and searching behavior of deer.

Can.

J.

Zool. 67: 24-32.

Homoya, M.A., D.B. Acad.

Sci. 94:

Abrell, J.R. Aldrich, and T.W. Post. 1985.

The

natural regions of Indiana. Proc. Indiana

245-268.

Kohlman, S.G. and K.L. Risenhoover. 1994. depletion. Can.

Spatial and behavioral response of white-tailed deer to forage

Zool. 72: 506-513.

J.

Korschgen, L. 1962. Foods of Missouri deer, with some management implications.

J.

Wildlife Manage. 26:

163-172.

Marquis, D.A. 1974. The impact of deer browsing on Allegheny hardwood regeneration. U.S. Dep. Agr., U.S. Forest Serv. Paper NE-308, 8 pp.

McArthur, C, C.T. Robbins, A.E. Hagerman, and T.A. Hanley. 1993. Diet selection by a ruminant generalist browser relative

McCaffery, K.R., Wildlife

J.

Manage.

Mumford, R. and

J.

Can.

to plant chemistry.

Tranetzki, and

J.

J.

Piechura,

Zool. 71: 2236-2243.

Jr.

1974.

Summer

foods of deer

in

northern Wisconsin.

J.

38(2): 215-219.

Whitaker,

Jr.

1982.

Mammals

of Indiana. Indiana Univ. Press, Bloomington, Indiana,

537 pp.

Nixon, C, M.W. McClain, and K.R. Russell. 1970. Deer food habits and range characteristics

in

Ohio.

J.

Wildlife Mgt. 34(4): 870-886.

Parker, G.R. and J.E.

Van Kley. 1993. Brown County

State Park: Final report on vegetation

damage by

white-tailed deer. Unpubl. report.

Smith,

W.P

Strole, T.A.

central Illinois forests. Natur.

Van Kley,

Mammalian

1991. Odocoileus virginianus.

Spec. 388: 1-13.

and R.C. Anderson. 1992. White-tailed deer browsing: Species preferences and implications for

J.E.

Areas

and G.R. Parker. 1993.

J.

An

12(3): 139-144.

ecological classification system for the Central

Hardwoods

Region: The Hoosier National Forest, Indiana. Proc. 9th Central Hardwoods Conf., U.S. Dep. Agr., Forest Serv.,

North Central Forest Exp.

Westoby, M. 1974.

An

Stat.,

Gen. Tech. Rep. NC-161, pp. 308-326.

analysis of diet selection by large generalist herbivores.

Amer. Natur. 108: 290-304.